Chipworks publishes PS4 chip die analysis

The CXD90026G semi-custom APU found in Sony's next-generation PS4 console has been ripped open, revealing some interesting facets to its design.

Chipworks has published an initial analysis of the semi-custom AMD accelerated processing unit (APU) that powers Sony's PlayStation 4, following the console's North American launch.

The PS4 is a departure from the company's traditional approach: where the original PlayStation, the PS2 and the PS3 all used somewhat esoteric instruction set architectures - MIPS in the first two iterations and the hybrid Power architecture known as Cell in the third - the company's forth console generation uses the familiar 64-bit x86 architecture. As before, however, the chip at the heart of the console isn't an off-the-shelf component but a semi-custom design tweaked to Sony's requirements in unspecified ways by manufacturer AMD.

Now, semiconductor expert Chipworks has offered glimpse of just what AMD has put into the CXD90026G chip at the heart of Sony's next-generation console - and in doing so offered hints as to what to expect from Microsoft's rival Xbox One when it launches on Friday.

According to the company's initial technical analysis, the PS4's CXD90026G processor features a die size of 348mm² - a serious increase over the combined 228mm² die size of the CPU and GPU found in the PS3. Imaging of the chip shows the expected eight Jaguar processing cores present and correct, split into two quad-core blocks squished into the left-hand edge of the die. A surprise, however, is a total of 20 Graphics Core Next Compute Units for a total of 1,280 shaders - more than the expected 18 blocks totalling 1,152 shaders.

Before readers with PS4 pre-orders get too excited, however, it appears that two of the 20 GPU units are inactive - suggesting that the extra blocks are there to improve yield at manufacturing, allowing for up to 10 per cent of the GPU components to fail without affecting the final performance of the chip. Should yields improve, however, it's possible Sony could release an updated PS4 with all 20 GPU units activated - although whether it would split its customer base in this fashion is questionable, even if the extra power is only used to smooth out performance slightly.

The floor plan of the die also reveals memory controllers located on three edges, matching the layout of the motherboard which places GDDR5 memory modules at the left, top and bottom of the APU. The remaining edge, at the right-hand side of the chip, is used for communication to components on the remainder of the motherboard.

The company's analysis also suggests that the twelve-layer design is manufactured by AMD using Taiwan Semiconductor (TSMC) High-K Metal Gate (HKMG) process at a 28nm node - and concludes it's likely exactly the same process AMD uses for its latest Radeon GPUs.

While Chipworks' analysis reveals much about Sony's custom APU, the real secrets will likely only show themselves when the rival Xbox One - with its own semi-custom eight-core AMD APU - launches on Friday and offers the opportunity for the same analysis and a direct comparison between the design of the two parts.

Originally Posted by dyzophoriaI doubt sony will release a version with all 20 GPU units active

It's not unheard of: the CPU in later-model PS2s ran faster than it did in launch models. It won't happen tomorrow, but a mid-life performance boost to coincide with the release of the PlayStation 4 Slim? I wouldn't rule it out, although I wouldn't bet my house on it either.

Originally Posted by dyzophoriaI doubt sony will release a version with all 20 GPU units active

It's not unheard of: the CPU in later-model PS2s ran faster than it did in launch models. It won't happen tomorrow, but a mid-life performance boost to coincide with the release of the PlayStation 4 Slim? I wouldn't rule it out, although I wouldn't bet my house on it either.

maybe, but it would just be harder for developers to optimize their games though, I could be wrong though, unless the SDK for sony will easily allow for a game to optimize itself dependent on system speed

Originally Posted by dyzophoriamaybe, but it would just be harder for developers to optimize their games though [...]

No optimisation necessary. You design for 18 units, and get 60FPS dipping to 50FPS during busy scenes; if your lucky punter has 20 units, they'll get 60FPS solid throughout the entire game. It's not like PC game developers optimise for every graphics card on the market individually...

Originally Posted by Gareth HalfacreeNo optimisation necessary. You design for 18 units, and get 60FPS dipping to 50FPS during busy scenes; if your lucky punter has 20 units, they'll get 60FPS solid throughout the entire game. It's not like PC game developers optimise for every graphics card on the market individually...

PC developers don't, because they can't. Console developers, however, absolutely do. I don't see Sony activating the 2 CUs even if yields improve. They won't risk splitting their consumer base. Your PS2 CPU example is really stretching it. It originally ran at 295 Mhz, and the newer versions ran at 299 Mhz. A 4 Mhz increase is hardly comparable to the situation we have here.

Originally Posted by NarishmaPC developers don't, because they can't. Console developers, however, absolutely do. I don't see Sony activating the 2 CUs even if yields improve. They won't risk splitting their consumer base. Your PS2 CPU example is really stretching it. It originally ran at 295 Mhz, and the newer versions ran at 299 Mhz. A 4 Mhz increase is hardly comparable to the situation we have here.

Okay, here's a better example: when the Xbox 360 launched, you had a choice of hard drive or no hard drive models. Later, the version with no local storage went away - and games that required a hard drive started appearing. That's a pretty clear split of the user base: there was no way for an owner of a hard-drive-free Xbox 360 to play games which mandated the use of a hard drive, except buying a hard drive.

Sony, too, has a history of changing hardware quite dramatically. Okay, the PS2 CPU speed up was minor - but how about when the Emotion Engine went away from the PS3 NA launch to the PS3 European launch? Then PS2 compatibility went *completely* away post-launch.

Let's be clear, though: I'm not saying it *will* happen; I'm just saying it *could* happen.

Sorry Gareth, I think you're off-base here. Consoles are fixed targets, and imagine the uproar if gamers found out there was a lottery that might give you better performance? They'll just sit there returning consoles to retailers until they get one that is "better" - just like some Apple users did with MacBook Pro screens.

Sony will have disabled those two CUs for yield - their APU is a pretty hefty piece of silicon, so they need that margin for error to reduce costs.

You can't use things like hard drives, or backwards compatibility as examples of changes. The GPU is a key piece of the unit and drives the very development of the game, it won't change. The PS2 change was from 294.912Mhz to 299Mhz - a mere 5Mhz that will make precisely zero difference in reality, whereas two CUs will have a much bigger effect.

Using your HD example, a user who found that a HD was a requirement could simply go out and buy one to drop in. Yes, they'd be peeved it cost money, but it could be done. You can't swap out a CPU in a console.

Originally Posted by CeiConsoles are fixed targets, and imagine the uproar if gamers found out there was a lottery that might give you better performance? They'll just sit there returning consoles to retailers until they get one that is "better" - just like some Apple users did with MacBook Pro screens.

What lottery? Read back up-thread: I'm suggesting the upgrade could come alongside a complete console redesign. You wouldn't have some PS4s with 18 CUs and some with 20 CUs; you'd have PS4s with 18 CUs and PS4 Slims with 20 CUs. It'd be a selling point for the redesign, in fact: "Smaller! Thinner! Lighter! 10% more powerful!"

As for consoles being fixed targets, they're not: the Xbox 360, as but one example, has undergone several revisions in its lifespan. While the performance of the chip may have stayed the same, the process node and TDP have both changed since the console originally launched. There were people who upgraded to the Xbox 360 Slim because it was quieter than the launch design; I would imagine there would be even more people who would upgrade to a PS4 Slim if it came with the promise of a bit of extra graphics grunt.

Again, let me make something clear: I'm not saying Sony will release a 20-CU PS4 model, nor that it's even likely that it will release a 20-CU PS4 model; merely that it could release a 20-CU PS4 model.

Quote:

Originally Posted by CeiUsing your HD example, a user who found that a HD was a requirement could simply go out and buy one to drop in. Yes, they'd be peeved it cost money, but it could be done. You can't swap out a CPU in a console.

And nor would you need to: a hard-drive-less console can't run a game which requires a hard drive; an 18-CU console can run all the games that a 20-CU console can, just with 10% less graphical horsepower. That's, what, a variation of just 6FPS on a 60FPS game? I can't see anyone clamouring for refunds or free upgrades if Sony made the move in four or five years' time.

Okay, if it came with a re-design, Sony would be massively annoying every single person who had purchased an original PS4, because they then feel compelled to drop the money on a newer, faster, model. Sony's CPU bump on the PS2 was kept on the quiet to say the least, possibly because it literally made no difference to performance or possibly because Sony didn't want to aggrieve their userbase.

You're using examples that don't work. Consoles are a fixed target in terms of their CPU/GPU and RAM - so basically their performance. Things like die shrinks benefit the console manufacturer on the whole by reducing prices and also allowing peripheral gains such as reduced power draw or noise. There were/are people who upgraded their Xbox 360 or PS3 to take advantage, but they'll be in the minority. Lots of console gamers buy in to the system on the premise that they don't have to worry about upgrades, and that the unit they buy at the launch will play the games that come at the end.

However, we are in agreement. Sony could release a 20 CU model. But they won't.

Originally Posted by CeiLots of console gamers buy in to the system on the premise that they don't have to worry about upgrades, and that the unit they buy at the launch will play the games that come at the end.

And, as mentioned up-thread, an 18 CU PS4 bought at launch will be able to play the games that come at the end of the console's lifespan, regardless of whether or not a 20 CU exists. Having 10% less graphical horsepower wouldn't render games unplayable.

Quote:

Originally Posted by CeiHowever, we are in agreement. Sony could release a 20 CU model. But they won't.

Forget 2 shader units on a refresh, what would be even better of course being PC based hardware is perhaps AMDs latest and greatest APU in the future but with full backward compatibility, buying new consoles like people buy iphones, now that would be good. Extra bells and whistles for PS5 but games fully functional on PS4, should be easy for devs as it would just need PC like quality settings which the engines probably already support. I'd rather see that in a couple of years, need something to drive my 4k screen I'll no doubt buy in a year or two.

I think when they PS5 launches they'l stick with x86 (unless something bonkers happens in the meantime), which may allow backwards compatibility. However, by that point they'll be targeting 4K, so I'm not sure we'll see dual-release games as they won't even fit on BluRay discs.

Why? The gaming industry is full of money - in fact, it was one of Sony's few divisions to make a profit recently. I can't exactly foresee people not playing games in another 7 years, just that our definition of a console may shift slightly.

This generation of consoles is the most PC-like[1], with two of the three using near off-the-shelf PC components running the AMD64 x86 instruction set with only minor customisation. Both AMD64 consoles are, arguably, interchangeable[2] and vary only in their performance. Further, they will be receiving competition in the near future from Valve's Steam Boxes as well as the competition they have always faced from traditional PCs.

Why have Sony and Microsoft opted to build what are, basically, compact PCs with locked-down operating systems? Because there won't be any more consoles: after this, both the Xbox and PlayStation brands will exist only as a shell over commodity hardware. The next generation of consoles will actually be just the OS, divorced from the hardware entirely - with the move to sharing an instruction set with commodity PCs being the first step on that path.

Why would they do this? Designing and building a console is hard, it's expensive, and you make the barest of profit on the hardware. Publishing software, that's where the money is. Imagine a world where instead of buying a PlayStation 5 or Xbox Two, you download the PlayStation OS or Xbox OS. Just like Valve plans to release SteamOS as well as using it as the basis for its Steam Box consoles, there's the argument for a future where Sony and Microsoft release their own operating systems for gaming systems - or, in Microsoft's case, build it into a Windows 12 Gaming Edition OS.

They wouldn't do that, would they? Well, why not? It'd save 'em a tonne of money, and they've already made moves in this direction: Sony allows third parties to label their Android devices as PlayStation Compatible, and both companies have second-screen apps for smart devices. Coupled with the move to hardware entirely compatible with an off-the-shelf PC, and you've got a path to the death of physical consoles for the next generation.

[1] Of the recent generations, anyway. Historically, it's not a new trend: the Commodore 64GS is the most obvious example here. Built by Commodore as a means of targeting the console market, it was a Commodore 64 minus the keyboard and most of the ports, and could only be used with expensive cartridge games. With the C64 also being able to play said cartridge games in addition to far cheaper tape games, including a keyboard, and having far greater expansion and educational capabilities while costing less than the 64GS, it was not a success. Popular with collectors these days, mind.

[2] Are too. Sure, the PS4 has slightly more powerful graphics and GDDR5 instead of DDR3 memory - but they're both locked-down PCs with AMD eight-core APUs, 8GB of RAM and SATA storage.

Disclaimer: do I think that's likely? Nah. Companies love having a shiny box to show off at the launch. Imagine people queuing at midnight at their local Game in order to take home a DVD containing the latest Xbox OS - not quite the same experience, is it?

It would go that in the next 5-6 years tablets and possibly phones will become ever more powerful, so why would you want a console sitting around when tablets may be powerful enough to run games and stream the content to a TV.

Lots of company's are now demonstrating streaming games from the device to a TV (Shield, Steam OS) why have a box tied to a TV for games when it maybe possible in 5-6 years to have a tablet powerful enough to stream games to any TV you happen to be near, along with wireless controller.

EDIT: posted before i read Gareth's post

Quote:

Originally Posted by Gareth HalfacreeDisclaimer: do I think that's likely? Nah. Companies love having a shiny box to show off at the launch. Imagine people queuing at midnight at their local Game in order to take home a DVD containing the latest Xbox OS - not quite the same experience, is it?

No it isn't, but Microsoft have talked about one OS for everything, they have the Surface and the phones. Who knows maybe tablets and phone will have enough processing and GPU power to run proper games, so people wouldn't be buying an Xbox OS but instead buying the latest's Microsoft tablet that can be used for everything including connecting up to a TV to play games on.

Originally Posted by Gareth HalfacreeIt's not unheard of: the CPU in later-model PS2s ran faster than it did in launch models. It won't happen tomorrow, but a mid-life performance boost to coincide with the release of the PlayStation 4 Slim? I wouldn't rule it out, although I wouldn't bet my house on it either.

Dont worry; I'll bet your house for you!

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